Power supply question...

Hi everyone, sorry for the incredibly basic question but I've just got my hands on a few pedals and cant be bothered with the unreliability of powering them all with batteries so I am looking to get some kind of power supply.

Now I did a few searches on here and everyone keeps mentioning onespots. Can someone explain the benefit/differences of a onespot over say something like this:

Yeah, that other supply doesn't appear to offer any advantage over a onespot.

As far as polarity, you shouldn't have to worry if all your pedals are fairly recent 9v, as most builders use the same polarity. But you should definitely take note of your pedals' polarity before using any power supply just to be safe.

100mA is fine for many (not all) pedals, Things like DigiTech pedals will need more than that. Best to check the power consumption of the pedals you wish to power in the technical specs before using it.

I have a feeling all of the sockets will be tied together, so really the power consumption of all the pedals combined should not be any more than 1000mA (or 1A). I cannot say for sure (without opening one up) but I do own a power supply much like that one which has all of the sockets tied together.

More or less all pedals use centre negative power as it is easy to use off the shelf parts to switch between battery and external power. Unless you have some unusual and or vintage pedals, that power supply should be fine.

Some pedals do sound ever so slightly different running off mains power, mainly because of the change in voltage (battery voltage decreases with drain) and resistance (internal resistance gets higher with drain) that occurs with batteries. Don't really need to worry about this though.

I've read that onespots can be a tad on the noisy side, is this the case? my trace already hums a bit so i'd prefer not to encourage it...

all pedals are new and pretty standard stompbox variety OD's /chorus / tuner made by joyo, boss etc. is there a straight forward way to check the power consumption (is it just written on the pedals somewhere?).

That supply you linked looks fancy, but nothing that cheap is a safe bet if it a) doesn't have a huge and positive reputation, and b) has too many 'nice' features. Features+ cheap= probably not good.
The 1spot is just a well-designed utilitarian wallwart, and it can power A LOT of pedals, and if you put a little effort in with zip ties it can be just as neat and organized as a multi-plug supply.